Abstract
The Central Atlantic Magmatic Province (CAMP) is the most aerially extensive magmatic event in Earth’s history, but many questions remain about its origin, volume, and distribution. Despite many observations of CAMP magmatism near Earth’s surface, few constraints exist on CAMP intrusions at depth. Here we present detailed constraints on crustal and upper mantle structure from wide-angle seismic data across the Triassic South Georgia Rift that formed shortly before CAMP. Lower crustal magmatism is concentrated where synrift sedimentary fill is thickest and the crust is thinnest, suggesting that lithospheric thinning influenced the locus and volume of magmatism. The limited distribution of lower crustal intrusions implies modest total CAMP volumes of 85,000 to 169,000 km3 beneath the South Georgia Rift, consistent with moderately elevated mantle potential temperatures (<1500 °C). These results suggest that CAMP magmatism in the South Georgia Rift is caused by syn-rift decompression melting of a warm, enriched mantle.
Highlights
The Central Atlantic Magmatic Province (CAMP) is the most aerially extensive magmatic event in Earth’s history, but many questions remain about its origin, volume, and distribution
P-wave velocity models based on wide-angle seismic reflection/refraction data acquired along two profiles across the South Georgia Basin during the SUwanee Suture and GA Rift basin experiment (SUGAR) constrain the depth of basin fill, crustal thickness, and the volume and distribution of CAMP magmatic additions (Fig. 2)
The combined geophysical, geological, and geochemical constraints on magmatism in the Southeastern US can be explained by decompression melting and emplacement of lower crustal intrusions during continental extension between 230 and 205 Ma
Summary
The Central Atlantic Magmatic Province (CAMP) is the most aerially extensive magmatic event in Earth’s history, but many questions remain about its origin, volume, and distribution. The limited distribution of lower crustal intrusions implies modest total CAMP volumes of 85,000 to 169,000 km[3] beneath the South Georgia Rift, consistent with moderately elevated mantle potential temperatures (
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